Paper guides for continuous feed printing

ABSTRACT

A system for providing damage-free travel of media on media path in an image-forming apparatus is described. The system includes a roller configured to transport media on the media path and one or more guides positioned at either end of the roller. Each guide includes an inner end extending into the media path, and an outer end extending beyond the media path, the outer end having a height greater than the height of the inner end. Moreover, the surface between the inner end and the outer end is concave in shape.

TECHNICAL FIELD

The presently disclosed embodiments generally relate to continuous feedprinting environments, and more particularly, to media handling duringprinting processes.

BACKGROUND

A continuous feed (CF) printer, as opposed to cut sheet printers, printson a band/roll of paper and not on discrete separate sheets. The roll ofpaper is separated into single sheets after printing is complete. CFprinting systems are used in many industries, such as banks, insurancecompanies, and print shops for printing items such as forms and checks.These systems generally provide high-speed production print jobs withfewer registration errors than cut sheet printing systems during duplexprinting.

Typically, CF printing systems require significant transportation ofpaper along the media paths. For example, during duplex printing, two CFprinters print on the same continuous sheet of paper; the second printerreceives paper from the first printer and prints on the unprinted side.A single paper path links the two printers. Generally, in multiplexprinting, several printers are part of the same paper path.

The term “paper path” is used in the art to refer both to the routefollowed by media through an imaging system and to equipment employedfor handling the media on that route. In a continuous feed system, thepaper path includes equipment such as shafts, rollers, and divertingmechanisms, all used for transporting paper through the system.

With paper moving rapidly through a continuous feed system, maintainingthe paper exactly positioned on the paper path assumes significantimportance. Anisotropy of the paper, however, can cause the paper todrift out of position. Environmental conditions, such as humidity andtemperature, can cause the paper to stretch or otherwise change shape,resulting in the paper drifting from the desired location on the paperpath. Conventionally, guides are attached to rollers to provideappropriate paper alignment. Rings located at the ends of shafts orrollers are designed to prevent side-to-side movement.

That solution may not function properly for many media, however.Lightweight media, under about 60 gsm, suffer from damage caused by thering-shaped guides. Some systems have employed electronic sensors toactuate a roller to compensate skew. This solution is, however,expensive.

It would be highly desirable to have a simple and cost-effective guidethat prevents media damage and printing errors for lightweight mediasheets.

SUMMARY

The present disclosure describes a system for promoting damage-freetravel of media on a media path in an image-forming apparatus. Thesystem includes a roller configured to transport media on the media pathand one or more guides positioned at either end of the roller. Theguides extend in a direction transverse to the media path. Each guideincludes an inner end extending into the media path, and an outer endextending beyond the media path, the outer end having a height greaterthan the height of the inner end. Moreover, the surface between theinner end and the outer end is concave in shape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary embodiment of a media path in acontinuous feed printing system.

FIG. 2 illustrates an exemplary embodiment of a guided media system fortransporting damage free media using a media guide.

FIG. 3 illustrates the sectional view of the guided media systemdiscussed in FIG. 2.

FIGS. 4 and 5 illustrates another exemplary sectional view of the mediaguide depicted in FIG. 2.

DETAILED DESCRIPTION

The following detailed description is made with reference to thefigures. Preferred embodiments are described to illustrate thedisclosure, not to limit its scope, which is defined by the claims.Those of ordinary skill in the art will recognize a number of equivalentvariations in the description that follows.

Overview

The present disclosure describes various embodiments of a systemproviding damage-free control of media on a media path in animage-forming apparatus, such as a continuous feed printer. The mediapath includes equipment such as rollers for transporting media sheets.One or more media guides positioned at either end of the rollersfacilitate appropriate alignment of the media over the rollers. Theguides extend in a direction transverse to the media path having aninner end extending into the media path rollers and an outer endextending outwards. The height of the outer end is greater than theinner end, and the surface between these two ends describes a concaveparabola. These guides prevent edge damage by auto-positioning mediaonto the rollers. Moreover, this guide accommodates media of variableweight, especially lightweight media otherwise susceptible to edgedamage.

For purposes of description, the present disclosure is discussed inrelation to continuous feed printing systems; those skilled in the art,however, will appreciate that the subject matter disclosed may beapplicable to any image-forming device that may face media edge damagingissues. The term “media” used in the present disclosure refers tocontinuously fed media of paper, plastic, or other suitable material.Moreover, the terms “media”, “media sheet”, “sheet”, and “paper” areinterchangeable as used below.

Exemplary Embodiments

FIG. 1 shows a typical media path 100 for transporting media in aconventional printing system. For purposes of description, consider themedia path 100 as part of a conventional duplex printing system thatincludes two parallel simplex continuous feed printers 102 and 104 thatprint on either side of a sheet 106. As known to those in the art, oneCF printer accepts media that comes from the other and prints on itsunprinted side, providing duplex printing. As shown, the media outputfrom the CF printer 104 having print job on one side of the sheet 106 isdiverted to the CF printer 102. The media path 100 between the two CFprinters 102 and 104 includes rollers 108 or other known devices thatassist in transportation process. Those skilled in the art willcomprehend that such a media path may be present in any printing devicethat requires continuous sheet of paper to traverse form one device toanother.

In general, the sheet 106 traveling along the media path 100 is requiredto be under tension using known devices such as brakes. Such papersheets traveling under tension may experience misalignments thatgenerate printing errors. Misalignment may arise due to imperfections inmedia path equipment, such as manufacturing flaws, inappropriateadjustment of the media path equipment. For example, improperparallelism of the rollers 108 may divert the media from the desiredpath towards left or right.

Consequently, the media path 100 includes conventional guides 110 thatensure appropriate alignment of the sheet 106 over the rollers 108. Theguides 110 are employed to compensate for the imperfections in mediapath equipment. The guides 110 are ring-shaped structures that present aflat vertical surface to the edges of the sheet 106. As alreadydiscussed, the substantially vertical surface of the guides 110 maydamage media having lighter weight.

FIG. 2 and FIG. 3 depict a guided media system 200 illustrating anarrangement that provides damage-free media travel. FIG. 2 includesrollers 202 to transport a sheet 204 along a direction referred to asmedia path, depicted by an arrow 206, such as the media path 100. Thesection of the media path depicted here includes two rollers 202 fortransporting lightweight media. To prevent edge damage and enableappropriate alignment of the sheet 204, the system 200 employs guides208 positioned at either end of the rollers 202, extending in adirection transverse to the media path. The guided system 200 employsthe curved guides 208 along the media path 100 instead of theroller-shaped guides 110 employed in FIG. 1. As shown, the longitudinalaxis of the guides 208 may be substantially parallel to the longitudinalaxis of the rollers 202.

The guides 208 may be positioned by any convenient means that enablelateral displacement of the guides 208 along the longitudinal axis ofthe rollers 202 in order to accommodate media having variable width.Moreover, the guides 208 are positioned such that a portion of the mediasheet 204 passes over the guides 208. The cross-sectional views of theguide 208 in the 4-4′ and 5-5′ plane are discussed in the followingsections in connection with FIGS. 4 and 5.

FIG. 3 depicts a cross-sectional view of the guides 208 in the 3-3′plane. As shown, the guides 208 include an inner end 216 that extendstowards the media path and an outer end 218 extending out. The height ofthe inner end 216 is lower than that of the outer end 218, and thesurface between these two ends describes a substantially concaveparabola. As shown, the height of the inner end 216 is substantiallynegligible to avoid any damage to the media sheet 204. In oneimplementation, the surface of the guide 208 may be elliptical, orGaussian in shape. The curvature of the guide may be determined based oncharacteristics of the media, such as its Young's modulus, thethickness, and the characteristics of the system, such as the tension inthe media path, and the paper path configuration. The surface isconcave, and the radius of the curvature may be 5 inches, for example.In another implementation, the height of the outer end may be 1 inchgreater than the inner end. The guides 208 may be manufactured from ametallic material such as Aluminium or Stainless Steel, which may beeasily available and subsequently, promotes economy.

While traversing on the media path, typically the center of the mediasheet 204 aligns with the center of the gap between the two guides 208,and it should be understood that the media edges traverses a greaterpath length than the center of the sheet 204. As shown, the guides 208are positioned on the rollers 202 such that the distance between the twoguides is approximately equal to the width of the media traversing overthe rollers 202. A skew, however, may dislocate the media sheet 204towards the left or right. This dislocation results in advancing thesheet over the corresponding guide 208, and subsequently, increases thepath length in the region of the skew. The length extension increasesthe tension on the side of the sheet 204 towards the skewing direction,and the media sheet 204 tends to move in the opposite direction due tothe elastic characteristics. The difference in the path length pushesthe media sheet 204 to the lowest energy position, which is the centerof the gap between the guides 208.

Further, the advancement of the media sheet 204 over the curved surfaceof the guides 208 does not damage the media edges, as the parabolicshape presents a smooth surface to the media edges. Theseparabolic-shaped guides 208 accomplish damage-free transport of anymedia sheet weighting from 200 gsm to 40 gsm. It should be understoodthat the concepts set out here could be employed both in deviceshandling lightweight media, such as paper sheets, as well as transportsystems handling heavyweight sheets, such as corrugated cardboard.

FIG. 4 and FIG. 5 depict sectional views of the guide 208 in the plane4-4′ and 5-5′, respectively. FIG. 4 depicts the upper surface of theguide 208 in close proximity to the outer end 218. As clearly shown, theguide 208 outlines a convex upper surface 220. Further, each guide 208includes two openings 222 positioned and dimensioned to slidably receivethe rollers 202. FIG. 5 illustrates the sectional view of the guide 208in close proximity to the inner end 216. Due to the parabolic shape ofthe guides 208, the upper surface 224 is substantially flat. Moreover,the height of the guide 208 in FIG. 4 is greater than that in FIG. 5.

It should be noted that the description below does not set out specificdetails of manufacture or design of the various components. Those ofskill in the art are familiar with such details, and unless departuresfrom those techniques are set out, techniques, designs and materialsknown in the art should be employed. Those in the art are capable ofchoosing suitable manufacturing and design details.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.It will be appreciated that several of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Variouspresently unforeseen or unanticipated alternatives, modifications,variations, or improvements therein may be subsequently made by thoseskilled in the art which are also intended to be encompassed by thefollowing claims.

1. A system for promoting damage-free travel of media on media path inan image-forming apparatus, the system comprising: a roller configuredto transport media on the media path; and one or more guides positionedat either end of the roller and extending in a direction transverse tothe media path, each guide having: an inner end extending into the mediapath; and an outer end extending beyond the media path, the outer endhaving a height greater than the height of the inner end; and asubstantially concave guide surface between the inner end and the outerend.
 2. The system of claim 1, wherein the guide surface issubstantially parabolic.
 3. The system of claim 1, wherein the curvatureof the guide surface is determined based on: young's modulus of themedia; thickness of the media; tension in the media path; orconfiguration of the paper path.
 4. The system of claim 1, wherein eachguide is positioned at either end of the roller such that thelongitudinal axis of the guide is substantially parallel to thelongitudinal axis of the roller.
 5. The system of claim 1, wherein theguides are positioned at both the ends of the roller.
 6. The system ofclaim 1, wherein the guides are laterally displaceable on the roller toaccommodate media of variable width.
 7. The system of claim 5, whereinthe guides are positioned at the two ends of the roller such that thedistance between the two guides is approximately equal to the width ofthe media traversing over the roller.
 8. The system of claim 1, whereinthe guides are manufactured from a metallic material.
 9. A guide forpromoting damage-free travel of media on media path, the guidecomprising: an inner end displaceably positioned at either end of aroller, the inner end extending into the media path; an outer endextending outwards from the media path, the outer end having a heightgreater than the height of the inner end; and a substantially parabolicguide surface between the inner end and the outer end, the parabolicsurface prevents lateral displacement of the media on the media path.10. The guide of claim 9, wherein the guide is positioned at both theends of the roller.
 11. The guide of claim 9, wherein media traversesover the roller such that a portion of the media passes over the curvedguides.
 12. The guide of claim 10, wherein the guides are positioned atthe either end of the roller such that the distance between the twoguides is approximately equal to the width of the media traversing overthe roller.
 13. The guide of claim 9, wherein the guides are laterallydisplaceable on the roller to accommodate variable width media.
 14. Theguide of claim 9, wherein the parabolic surface of the guide directsmedia towards the center of roller.
 15. The guides of claim 9, whereinthe parabolic curve of the guides is determined based on: young'smodulus of the media; thickness of the media; tension in the media path;configuration of the paper path.